WAYNE E. SINCLAIR, DAVID PFLUGER, HAROLD LINNARTZ AND JOHN P. MAIER, Institute of Physical Chemistry, University of Basel, Klingelbergstr. 80, CH-4056 Basel, Switzerland.
A technique combining discharge modulation with frequency modulation absorption experiments has been developed for the sensitive detection of electronic spectra of carbon chain cations generated in a liquid-nitrogen cooled hollow cathode. The rotationally resolved spectra of the A2 X2 000 transitions of polyacetylene and cyanopolyacetylene cations have been obtained at Doppler limited resolution using this technique. The double modulation technique has been extended to the detection of species generated in a pulsed supersonic jet and preliminary results will also be presented.